nostr:npub1rxysxnjkhrmqd3ey73dp9n5y5yvyzcs64acc9g0k2epcpwwyya4spvhnp8 has a great guide on building a DIY BTC mining space heater with an underclocked S9: https://www.youtube.com/watch?v=csmHvuzUECU , with 3D printed kit from nostr:npub1lrjgpa9m2dl6esdah5pq7m005ymwh4glq4aet76q2zlz2f83esfsa2zvrj